1. Field of the Invention
The present invention relates to a laser measuring device and, more particularly, to a laser measuring device which is adapted to emit a laser beam in a predetermined direction from a fixed position so that the laser beam is used as a reference in locating a measuring object or in measuring the position of the measuring object. The laser measuring device of the invention is suitable for use in measurement of automotive bodies or in setting up of an architectural structure.
A known laser measuring device for automotive bodies has orthogonal rails arranged ahead of the automotive body and on one side of the same. A laser beam splitter is provided at the crossing of these rails. A laser beam is split by the laser splitter into two beams which run in parallel with respective rails. Each laser beam running in parallel with the rail is deflected at a right angle by a penta prism which is adapted to slide on each rail and is directed towards the automotive body. In this known laser measuring device, a scale is fixed on the rail so that the position of the penta prism can be read on the scale.
The known device just described suffers from a disadvantage in that it cannot conduct three-dimensional measurement because the laser beam runs only within planes, i.e., two dimensionally. In order to overcome this problem, it has been proposed to use a scale plate which is suspended vertically from the measuring point, such that the measurement in the vertical direction is conducted by applying a laser beam to the scale. This not only complicates the measurement but also restricts the measurable range because the suspension of the scale plate is impeded by various parts or members which are below the measuring point.
Another drawback of the conventional measuring method comes about because the laser beam is always emitted horizontally. For this reason the laser beam is inconveniently interrupted by parts or members and cannot reach the measuring point thus resulting in a measuring failure. This is particularly a problem when the measuring point is hidden deep in, for example, the engine room of an automobile. When measuring the distance between two points, the distance is determined through computation which is conducted on the basis of the values read on the scale which is fixed to the rail. In addition, a complicated computation is required for the determination of the position of the central point between these two points.